Thermal analysis of a box type solar cooker coupled with Fresnel lens

Abstract

The thermal analysis of a Box-type solar cooker (BTSC) coupled with two Fresnel lens magnifiers (FLMG) is presented in this paper. A time dependent numerical model based on heat balances occurring at different parts of the cooker was prepared and executed in a MATLAB program. To check the robustness of the model, the temperature variation of the cooker elements obtained by the mathematic modeling was compared with the experimental results. The comparison showed the average estimated error between the experimental and numerical values fell between 0.73–3.49 percentage. In order to check the effectiveness of the FLMG, First Figure of merit (F₁) and Second figure of merit (F₂) tests were performed as per international testing procedures. The first figure of merit value increased from 0.11 to 0.12 m² °C/W, converting the BTSC from B grade category to A grade. The Second figure of merit rose from 0.43 to 0.45 by utilizing the FLMG, indicating the improvement in heat exchange to the load in the cooking vessel. The temperature of all the components of the BTSC was increased by incorporating the FLMG. The paper also discusses the variation of different heat transfer coefficients coming to play in the cooker. Basmati rice was successfully cooked by the solar cooker in an interval of 58 min.